Packing and composition



July 12, 1932. 5 DE VRIES 1,866,758

PACKING AND COMPOSITION Filed Aug. 29. 1929 :10 j@ .43 .11 4 a J2 49 J9 I wwmmmmv/y wv W XQ 27 20 16 Human M 11111;! 4! ml 11 MHHA Patented July 12, 1932 UNITED STATES PATENT OFFHCE.

FENNO E. DE ITRIES, OF EVANSTON, ILLINOIS, ASSIGNOR TO CRANE PACKING COM- PANY, A CORPORATION OF ILLINOIS PACKING AND COMPOSITION Application filed August 29, 1929. Serial No. 389,156.

My invention relates to new compositions and improvements in packing embodying such compositions, more particularly metallic packing used in condensers, evaporators and the like, where the packing may be subjected to the action of liquids containing corrosive materials such as acid.

An object of the invention is to provide an improved packing whereby the packing may be effective for long periods of time, even though subjected to fairly high or variable temperatures or to liquids containing corrosive substances or to both. as in the case of a steam surface condenser, for example.

One object of the invention is to provide a cellulosic base, such as a cellulose derivative as a protective coating material for metal foil, with or without fillers to provide added resistance to corrosion which tillers may or may not be electrically conductive.

In carrying out my invention I apply to sheet metal such as lead foil, babbitt or the like in the form of sheets or strips a resistant coating, preferably a drying lacquer, such as a metal adherent coat having a nitrocellulose base, or similar material having a relatively stable and resistant cellulose derivative therein, such as the cellulose acetates, viscose, and other known forms which can be made into adherent flexible coatings that do not break or crack as the metal foil is deformed.

The metal so coated is adapted for various uses. In the present application I have em phasized the advantages resulting from forming it into a ring orinto a continuous length of packing by any one of a number of suitable methods, such as by rolling a long narrow strip of it onto itself in the form of a spiral to provide a ring, and afterwards pressing the same in a die; or the packing may be formed by helically winding a nar row strip of coated metal tape on a rotating cord and thereafter running the product through rollers to produce a rectangular cross section; or sheets or strips of coated metal may be crinkled to interlock it for the purpose of forming a flexible packing, or the metal may be otherwise deformed.

The present invention aims to improve the resistance to corrosion of such coated packings by incorporating certain fillers into the coating. Inert fillers, or pigments may be employed, yet the invention is not limited to them. Metallic or other electrically conductive particles may be incorporated into the coatings, giving electrically conductive properties; Certain metals may remain inert under the conditions of exposure, and the same or other metals may yield to corrosion forming oxides or other compounds which act like pigments and provide additional resistance or protection against further corrosion. Graphite, lamp-black or other forms of carbon are particularly desirable, especially graphite, because of its high degree of inertness and of its electrical conductivity.

I have discovered that the resistance of such coatings is increased when ordinary paint pigments, metal powders, carbon, metal oxides and other solid ingredients are incorporated into the coatings. The use of graphite in particular is highly effective in this direction, and in spite of the fact that the coating substance is ordinarily an electrical insulator, I have discovered that graphite and metals in comminuted form in the coating impart to it an appreciable electrical conductivity, so that the packing made with such compositions is also electrically conductive.

In order to illustrate the invention, I show in the accompanying drawing several illustrations of packing embodying the invention, in which Fig. 1 is a diagram illustrating suitable apparatus for coating, baking and winding a strip of metal foil to form a flexible packing rlng;

Fig. 2 is a sectional elevation of a suitable die for compressing the ring;

Fig. 3 is a perspective view of the ring cut open to show the internal construction;

Fig. 4 is an enlarged sectional elevation through the end of a condenser tube and the adjacent tube sheet showing a typical packing installation; and

Fig. 5 is a cross sectional enlarged view of coated foil with filler taken on the llne foil may be lead foil, Babbitt foil, or copper or aluminum, and in some cases coated with tin in advance. Each strip of foil is fed from the supply reel through a receptacle 12 containing a bath or liquid 13, such for example as a flexible nitrocellulose lacquer which is compounded for adherence to metal. I have tried nitrocellulose solutions and cellulose acetate solutions on smooth and shiny foil but find that they are not'suliiciently adherent to metal towithstand the deforming operations to which the coated foil is subjected. I have found that with certain varnish gums a suflicient adherence is ob tained.

The strip passes under a suitable roller 14 in the bath and then over a second roller 15- and then between wiping felts 16 to remove the surplus. coating. Said strip then passes through an oven 17, which in the form shown comprises a chamber lined with refractory material 18 and having aligned openings 19 at opposite ends thereof through which the coated foil strip entcrsand leaves the dryer.

The chamber is heated. from below by a suitable fuelv such asgas burners 20 and a suitable vent 2]. may beprevided above the oven.

The foil on leaving the dryer passes through a guide 22 and is supported'hy said guide at onev end and by the roller 15 at the other end, both; outside of. the dryer, being unsupported within the dryer. The temperature of the dryer and the speed at which the foil is. passed through it may vary under different conditions depending on the char actor of the coating and. the particular type of service for which the packing is intended.

After passing beyond the guide 22, the foil with the protective coating on it is wound on a suitable reel 23 driven by a gear and pinion 24 and 25, the latter being rotated by any suitable source of power such as a belt 26 running over a. pulley. on a shaft. 27, the latter being driven by a belt Q'Sfrom a motor 29. The shaft 27 extends across the machine and operates a plurality of reels 23,. whatever number may. be desired, and the dryer of course has a corresponding series of aligned openings. 1919 therein through which strips of foil may be fed from the spools 10. In other words a number of lengths of foil may be coated simultaneously.

As the foil leaves the guide 2:2 and is wound on the spool 23, it is pressed down against the latter by a rotatable wheel 30 carried by a pivoted arm 81. Said wheel is of substantial weight and rolls the foil down in smooth layers.

These finished rolls are thereafter unwound as the foil is being fed into the machine for forming the packing, in case it is so used. It is therefore necessary that the reel of foil be unwound without sticking or tearing and the process and apparatus described are so regulated and designed as to obviate this difiiculty.

After the coated metal foil is formed it is wound on a suitable mandrel to form a helical. ring of predetermined diameter, width and thickness. The ring 32 thus formed, is there after pressed in a die 33 as shown in Fig. 2, during which operation the substantially concentric layers of thin sheet metal fold themselves back and forth to form, in cross section, wavy lines or interfi-tting accordion pleated layers, the four outer surfaces. of the ring, however, beingsmooth and compact. The finished ring, if subjected to: side compression, i. e. in a direction parallel to its central axis, tends to expand radially inward and outward. lVhere such a ring is used for packing the ends of condenser tubes as in Fig. 4, for example, one or more of said rings are slipped over the end of the condenser tube and caulked by special tools and may thereafter be further compressed by aferrule 35 of the usual form, if desired, although the ferrule may be dispensed with. Additional intervening fibre washers 36 may be employed as expansion rings. The opening in which the ferrule is received is screw threaded and the metallic rings are compressed by a caulking tool which upsets these metallic rings, outwardly and inwardly, completely filling the threads and pressing against the condenser tube with an evenly distributed pressure, resulting in the establishment of a water tight and air tight joint which, however, permits the tube to move back and forth longitudinally a slight distance unc er temperature variations, without breaking the seal.

In many condenser installations the cooling water which flows through the tubes is contaminated, as it is usually taken from rivers or from the ocean where the plant is located on tide water. Considerable diffi culty has been encountered heretofore due to disintegration of the tubes and deterioration of the packing itself, caused by exposure to air and to the effect of the air in the water, as well as agitation and turbulence.

The metal of whichthe packing is formed is very thin and oxidizes when not protected, resulting in holes forming in the metal, in the course of time.

Metallic packing formed by the method described herein is protected against deterioration due to acid in the water, salts or other contaminating substances. For-example, cut edges of tin coated lead foil present a galvanic couple to electrolytes in solution, and

the coating of varnlsh insulates this couple from the electrolyte. This coating is even more flexible than tin coated lead foil itself and is not broken mechanically Without also breaking the foil. It is of such character that it is not damaged during the compression of the ring within the die. The metallic packing is not affected by the heat due to the presence of the exhaust steam which surrounds the condenser tubes.

Not only must the coated strip be capable of being rolled up and unrolled without sticking or tearing, but also must not stick to the condenser tube after it has been installed. The cellulosic coated foil has a longer life in the uses described than does the bare foil packing, but I have found in comparative tests that the resistance is greatly increased by adding fillers to the coating materials, such as barites, zinc oxide, iron oxide, lead oxide, silica, Zinc sulphide, bronze powder, zinc dust, aluminum dust, graphite, lamp-black, etc.

I prefer graphite, because it is electrically conductive and chemically inert. found that in coatings of the kind here referred to, there is electrical conductivity because of the presence of carbon particles. Metals likewise give the same result, but these are subject under some conditions to corrosion forming products, like oxides, hydroxides, etc., which are more bulky than the orig inal metal particle, and which products fill voids in the packing. Therefore the use of metal is likely to result in the formation of some of the same quality of filler asis obtained when oxides and non-metallic fillers, such as pigments, are first employed.

The use of conductive packing keeps the metal parts and the packing at more or less equal potentials, and minimizes electrolytic corrosion resulting from differences of potential.

In Fig. 5, the metal foil is indicated as 37, the coating as 38, and the filler as 39.

The coating base may be a soluble cellulose derivative such as nitrocellulose, suitably modified and prepared for application to form an adherent coating. Nitrocellulose alone in solution with a volatile solvent evaporates to form a coating which adheres poorly or not at all to foil when the coated foil is deformed. I have discovered that the presence of varnish gums in the lacquer, such as is found in some commercial lacquers, causes sufficient adherence or such perfect adherence that the foil ma} be deformed into a packing. For example, a composition containing Parts Rosin Acetone 4O Nitrocellulose solution containing 1 pound nitrocellulose per gallon 20 is suitably adherent. Commercial lacquers known in the trade as Nikolas A5 and Nikolas No. 20 Red (containing a pigment) I have are very suitable. I have incorporated graphite into the Nikolas A5 and also into the exemplary composition above specified in the proportion of two parts graphite to the formula proportions given. However, I have found that the presence of the amount of graphite has a tendency to reduce the adherence of the same coating used without the graphite. I have been able to improve adherence by employing a thinner coating, that is by using more solvent at the same time increasing the content of graphite, giving a suitable coating as follows:

Parts Rosin 1 Acetone 80 Nitrocellulose solution (one pound nitrocellulose per gallon) 20 Graphite powder (amorphous) 4 The packing referred to,as far as the mechanical features are concerned, is described more fully in l/Valton Patent 1,543,963 is sued June 30, 1925, to Crane Packing Company and the machine for making it is described in Cody Patents No. 1,642,431 issued September 13, 1927, and No. 1,646,992 issued October 25, 1927. In my copending application Serial No. 389,155, also filed August 29, 1929, there is described another packing, using as a base a finally reacted synthetic resin, rather than a cellulose derivative, as a protective agent on the foil.

What I claim is:

1. A metallic packing comprising a me chanically deformed metallic foil having an adherent cellulosic coating of a flexibility at least equal to the flexibility of the foil and an electrically conductive filler incorporated in said coating.

2. A metallic packing comprising a mechanically deformed and compressed metallic foil having an adherent cellulosic coating of a flexibility at least equal to the flexibility of the metal foil and an electrically conductive filler incorporated in said coating.

3. A metallic packing comprising a mechanically deformed metal foil and an adherent nitrocellulose coating of a flexibility at least equal to the flexibility of the metal foil and an electrically conductive filler incorporated in said coating.

4. A metallic packing comprising a plurality of layers of mechanically deformed metal foil each layer of which is covered with a cellulosic coating having a flexibility at least equal to the flexibility of the foil and an electrically conductive filler incorporated in said coating.

5. A metallic packing comprising a plurality of layers of mechanically deformed metal foil each layer of which is covered with an adherent nitrocellulose coating having a flexibility at least equal to the flexibility of the foil and an electrically conductive filler inco rated in said coatin 6. metallic packing comprising a mechanically deformed metallic foil having a coating of nitrocellulose incorporating a varnish gum, said coating having a flexibility at least equal to the flexibility of the foil and an electrically conductive filler incorporated in said coating.

7 A metallic packing comprising a me chanioally deformed metallic foil having an adherent cellulosic coating of a flexibility at least equal to the flexibility of the foil and graphite incorporated in said coating to render the coating electrically conductive.

8. A metallic packing comprising a mechanically deformed metallic foil having a coating of nitrocellulose incorporating a varnish gum, said coating having a flexibility at least equal to the flexibility of the foil and graphite incorporated in said coating.

In testimony whereof I have subscribed my name.

FENNO E. DE VRIES. 

